A known vacuum glass panel includes a pair of glass plates with a vacuum space between the pair of glass plates. The vacuum glass panel is also referred to as a sealed insulating glass. In the vacuum glass panel, the vacuum space reduces thermal conduction, and therefore, the vacuum glass panel has an excellent thermal insulation property. In producing the vacuum glass panel, two glass plates which are paired are bonded to each other with a gap therebetween to form an inner space, gas in the inner space is exhausted, and the inner space is hermetically sealed, thereby forming the vacuum space.
In the vacuum glass panel, the two glass plates are bonded to each other by an adhesive material different from the glass plates, which may reduce the adhesive strength of a bonded portion of the glass plates. A reduction in adhesive strength may lead to problems such as breakage of the vacuum glass panel and deterioration of the thermal insulation property due to entrance of air into the vacuum space. Thus, it is important to increase the adhesive strength of the bonded portion of the glass plates. In particular, a vacuum glass panel including a heat reflective film provided on an inner surface of at least one of glass plates of the vacuum glass panel further requires an increased adhesive strength of the glass plates while maintaining a thermal insulation property obtained by the heat reflective film and a vacuum.
Patent Literature 1 discloses a sealed insulating glass including a pair of glass plates and a low-emissivity (LOW-E) film formed on a surface of one of the pair of glass plates, wherein the glass plates are bonded to each other at a portion on which the LOW-E film is not provided. However, a space between the pair of glass plates is not a vacuum, and therefore, the sealed insulating glass panel does not have a high thermal insulation property.